Submitted by Rosivalda Pereira (mrs.pereira@ufma.br) on 2017-05-10T20:18:37Z No. of bitstreams: 1 AdrianaLeal.pdf: 1605345 bytes, checksum: 700a558a6725b2db9159b45c403c2cbb (MD5) / Made available in DSpace on 2017-05-10T20:18:37Z (GMT). No. of bitstreams: 1 AdrianaLeal.pdf: 1605345 bytes, checksum: 700a558a6725b2db9159b45c403c2cbb (MD5) Previous issue date: 2016-02-29 / Fundação de Amparo à Pesquisa e ao Desenvolvimento Científico e Tecnológico do Maranhão (FAPEMA) / Objectives: To evaluate the effect of airborne-particle abrasion with niobium phosphate bioglass (NbG) microparticles on the bond strength (µTBS) and longevity of an adhesive system to different dentin substrates. Methods and Materials: Caries-free molars were used in this study. The dentin surfaces were evaluated in three groups: (1) Control – Healthy Dentin; (2) Partial removal of carious tissue; (3) complete removal of carious tissue. Half the teeth in each group were submitted to airborne-particle abrasion with NbG microparticles (15s/1cm/5bar). After this, the adhesive Clearfil S3 was applied and composite buildups were constructed incrementally; and specimens were longitudinally sectioned to obtain bonded sticks (1.0 mm2) to be tested in tension (0.5 mm/min) immediately or after 6 months of storage in water. The fracture patterns were evaluated by stereomicroscope (40x) and then by scanning electron microscopy (SEM). The data were analyzed by the Kruskal-Wallis (post-hoc Dunn) and Mann-Whitney tests (α=0.05). Results: Healthy dentin showed the highest bond strength (µTBS). Airborne-particle abrasion with NbG increased the µTBS values in the complete caries removal group. The bond strength values in the 24-hr period were higher than those at 6 months. In the majority of the specimens the fracture mode was adhesive/ mixed. Conclusion: The authors concluded that airborne-particle abrasion on dentin with NbG particles increased the µTBS in the group in which carious dentin was completely removed. / Objetivo: Avaliar o efeito do jateamento de micropartículas de vidro niobofosfato (NbG) na resistência de união (RU) e na longevidade de um sistema adesivo em diferentes substratos dentinários. Dezoito molares extraídos livres de cárie foram usados. As superfícies de dentina foram avaliadas em três grupos: (1) Controle – Dentina Sadia; (2) Remoção parcial do tecido cariado; (3) Remoção total do tecido cariado. Metade dos dentes de cada grupo sofreu um jateamento com partículas de NbG (15s/1cm/5bar). Em seguida o adesivo Clearfil S3 Bond Plus foi aplicado e uma coroa de resina composta foi construída. Os dentes foram seccionados para obtenção dos espécimes (1,0 mm2) e submetidos ao teste de microtração (0,5 mm/min) imediatamente e após 6 meses de estocagem em água. Os padrões de fratura foram avaliados usando estereomicroscópio (40x) e levados ao microscópio eletrônico de varredura (SEM). Os dados foram analisados pelos testes Kruskal-Wallis (pos-hoc Dunn) e Mann-Whitney (α=0.05). Resultados: A dentina sadia apresentou os maiores valores de RU. O jateamento com NbG aumentou os valores de RU no grupo remoção total. Os valores de RU no período de 24h foram superiores ao de 6 meses. A maioria das fraturas dos espécimes foi adesiva/mista. Conclusão: Os autores concluíram que o jateamento à dentina com partículas NbG aumentou a RU no grupo onde a dentina cariada foi totalmente removida.

Depuis l’apparition du circuit intégré, la performance des dispositifs semi-conducteurs est reliée à leur miniaturisation via le développement de procédés spécifiques tels que la lithographie. Néanmoins, la réduction des dimensions des dispositifs aux échelles nanométriques rend les étapes de patterning de plus en plus complexes et coûteuses (EUV, gestion de plusieurs passes de masque par couche et erreur de placement du/des masque(s) …) et pousse les fabricants de puces à se tourner vers des méthodes alternatives. Dans le but de réduire les coûts de fabrication des circuits intégrés, une approche bottom-up reposant sur l’utilisation de procédés de dépôts sélectifs est désormais envisagée, au détriment des approches conventionnelles top-down basées sur les procédés de lithographie. La solution de dépôt par couche atomique (ALD) est une technique appropriée pour le développement d’un procédé sélectif en raison de sa très grande sensibilité à la chimie de surface. Ce procédé est appelé dépôt sélectif de zone (ASD pour Area Selective Deposition). Il est basé sur un traitement spécifique d'activation ou de désactivation des réactions chimiques de surface avec le précurseur et/ou le réactif en mode ALD. Ces modifications de réactivité peuvent être obtenues en utilisant une couche de germination (activation) ou des groupes organiques tels que des monocouches auto-assemblées (SAM) (désactivation). Une autre voie est de tirer parti du retard inhérent à la croissance (ou temps d’incubation) sur différents substrats. Dans cette thèse, nous avons développé un nouveau procédé ASD d’oxyde métallique en combinant un dépôt de couche atomique et une étape de gravure qui permet de bloquer la croissance sur substrat à base de silicium (Si, SiO2 et SiN) versus un substrat métallique (TiN). L'étape de gravure est réalisée par addition de NF3 dans un plasma d'oxygène tous les n cycles du procédé PEALD. Nous avons utilisé ce procédé pour le dépôt de deux oxydes actuellement à l'étude pour les applications de mémoires résistives non-volatiles : Ta2O5 et TiO2. Le but des dépôts sélectifs pour l'application mémoire est de réaliser des points mémoires localisés métal/isolant/métal en intégration 3D verticale dite VRRAM. / At advanced nodes, lithography starts to dominate the wafer cost (EUV, managing multiple mask passes per layer and pattern placement error….). Therefore, complementary techniques are needed to continue extreme scaling and extend Moore’s law. Selective deposition and etching is one of them because they can be used to increase and enhance patterning capabilities at very low cost. From all the different deposition processes, Atomic Layer Deposition (ALD) is maybe the most suitable technique to develop a selective process due to its very good coverage property and its high surface sensitivity. This process is called Area Selective Deposition and is a selective deposition process for bottom-up construction It is usually based on a specific surface activation or deactivation treatment in order to activate or limit / inhibit chemical reactions with the ALD precursor / reactant. This surface modifications are usually obtained by using seed layer (activation) or organic groups such as Self-Assembled Monolayers (SAM) (deactivation). Another pathway for selective area deposition with ALD is to take advantage of the inherent substrate-dependent growth initiation: this is inherent selectivity based on difference of nucleation delay. In this thesis, we have proposed a new ASD process of thin oxide by combining atomic layer deposition and etching step (super-cycle) for a 3D Vertical RAM integration. This allows the selective growth of a thin oxide on a metal substrate without deposition on an insulator and/or a semi-conductor substrate(s). The etching step is achieved by NF3 addition in an oxygen plasma every n cycles of the PEALD process allowing (1) to etch the oxide layer on Si and/or SiO2 surface while keeping few nanometers of oxide on TiN substrate and (2) to passivate this two surfaces and to add a new incubation time on Si or SiO2 substrates. We used this process for the deposition of two oxides that are currently under study for non-volatile resistive memories applications: Ta2O5 and TiO2. The intention for memory application is to realize a crosspoint memory in Back-End level from a pattern area or a trench area without the photolithography step.

Nous étudions la possibilité de réaliser des cellules à base de diséléniure de cuivre, indium et gallium (CIGSe) à absorbeur ultra-mince, en réduisant l’épaisseur de la couche de CIGSe de 2500 nm jusqu’à 100 nm, tout en conservant un haut rendement de conversion.Grâce à l’utilisation d’outils de simulation numérique, nous étudions l’influence de la réduction d’épaisseur de l’absorbeur sur les paramètres photovoltaïques de la cellule. Une importante dégradation du rendement est observée, principalement attribuée à une réduction de la fraction de lumière absorbée par le CIGSe ainsi qu’à une collecte des porteurs de charge réduite dans les dispositifs ultraminces. Des solutions permettant de surmonter ces problèmes sont proposées et leur influence potentielle est numériquement simulée ; nous démontrons qu’une ingénierie de face avant (couche tampon alternative, couche anti-réfléchissante…) et de face arrière (contact arrière réfléchissant, diffusion de la lumière) sur une cellule CIGSe à absorbeur ultramince permet de potentiellement améliorer le rendement de la cellule solaire au niveau de celui d’une cellule à absorbeur référence (2.5 μm).Grâce à l’utilisation de techniques de gravure chimique sur des échantillons standards de CIGSe épais, nous réalisons des cellules solaires avec différentes épaisseurs d’absorbeurs, et nous étudions l’influence de l’épaisseur du CIGSe sur les paramètres photovoltaïques des cellules. Le comportement similaire aux simulations numériques.Une ingénierie du contact avant sur des cellules CIGSe à différentes épaisseurs est réalisée pour spécifiquement améliorer l’absorption dans la couche de CIGSe. Nous étudions l’influence d’une couche tampon alternative de ZnS, de la texturation de la fenêtre avant de ZnO:Al, et d’une couche anti-reflet sur la cellule solaire. D’importantes améliorations sont observées quelque soit l’épaisseur de la couche de CIGSe, ce qui permet d’obtenir des rendements de conversions supérieurs à ceux obtenus dans la configuration standard des dispositifs.Une ingénierie du contact arrière à basse température est également réalisée avec l’utilisation d’un procédé novateur combinant la gravure chimique du CIGSe avec un « lift-off » mécanique de la couche de CIGSe afin de la séparer du substrat de Molybdène. De nouveaux matériaux fortement réflecteur de lumière et précédemment incompatible avec le procédé de croissance du CIGSe sont utilisés comme contact arrière pour des cellules CIGSe ultra-minces. Une étude comparative en fonction de l’épaisseur de CIGSe entre des cellules avec contact arrière réfléchissant en Or (Au) et cellules solaires avec contact arrière standard Mo est effectuée. Le contact Au permet d’augmenter significativement le rendement de conversion des cellules solaires à absorbeur sub-microniques comparé au contact standard Mo avec un rendement de conversion supérieur à 10% obtenu sur une cellule CIGSe de 400 nm (comparé à 7.9% avec Mo).Afin de réduire encore plus l’épaisseur de la couche de CIGSe, jusque 100-200 nm, les modèles numériques montrent qu’il est nécessaire d’utiliser un réflecteur lambertien sur la face arrière de la cellule afin de maximiser l’absorption de la lumière. Un dispositif preuve de concept expérimental est réalisé avec une épaisseur de CIGSe de 200 nm et un réflecteur arrière lambertien, et ce dispositif est caractérisé par spectroscopie de transmission/réflexion. La réponse spectrale est déterminée en combinant des valeurs issues de simulation numérique et la mesure expérimental de l’absorption du dispositif. Nous calculons un courant de court circuit de 26 mA.cm-2 pour ce dispositif avec réflecteur lambertien, bien supérieur à ce qui est calculé pour la même structure sans réflecteur (15 mA.cm-2), et comparable au courant mesuré sur une cellule de référence de 2500 nm (28 mA.cm-2). L’utilisation de réflecteur lambertien pour des cellules CIGSe ultraminces est donc particulièrement adaptée pour maintenir de hauts rendements. / In this thesis, we investigate on the possibility to realize ultrathin absorber Copper Indium Gallium Di-Selenide (CIGSe) solar cells, by reducing the CIGSe thickness from 2500 nm down to 100 nm, while conserving a high conversion efficiency.Using numerical modeling, we first study the evolution of the photovoltaic parameters when reducing the absorber thickness. A strong decrease of the efficiency of the solar cell is observed, mainly related to a reduced light absorption and carrier collection for thin and ultrathin CIGSe solar cells. Solutions to overcome these problems are proposed and the potential improvements are modeled; we show that front side (buffer layer, antireflection coating) and back side (reflective back contact, light scattering) engineering of an ultrathin device can potentially increase the conversion efficiency up to the level of a standard thick CIGSe solar cell.By using chemical bromine etching on a standard thick CIGSe layer, we realize solar cells with different absorber thicknesses and experimentally study the influence of the absorber thickness on the photovoltaic parameters of the devices. Experiments show a similar trends to that observed in numerical modeling.Front contact engineering on thin CIGSe solar cell is realized to increase the specific absorption in CIGSe, including alternative ZnS buffer, front ZnO:Al window texturation and anti-reflection coating. Substantial improvements are observed whatever the CIGSe thickness, with efficiencies higher that the default configuration.A back contact engineering at low temperature is realized by using an innovative approach combining chemical etching of the CIGSe and mechanical lift-off of the CIGSe from the original Molybdenum (Mo) substrate. New highly reflective materials previously incompatible with the standard solar cell process are used as back contact for thin and ultrathin CIGSe solar cells, and a comparative study between standard Mo back contact and alternative reflective Au back contact solar cells is performed. The Au back reflector significantly enhance the efficiency of solar cell with sub-micrometer absorbers compared to the standard Mo back reflector; an efficiency higher than 10 % on a 400 nm CIGSe is obtained with Au back contact (7.9% with standard Mo back contact). For further reduction of the absorber thickness down to 100-200 nm, numerical modeling show that a lambertian back reflector is needed to fully absorb the incident light in the CIGSe. An experimental proof of concept device with a CIGSe thickness of 200 nm and a lambertian back reflector is realized and characterized by reflection/transmission spectroscopy, and the experimental spectral response is determined by combining simulation and experimentally measured absorption. A short circuit current of 26 mA.cm-2 is determined with the lambertian back reflector, which is much higher than what is obtained for the same device with no reflector (15 mA.cm-2), and comparable to the short circuit current measured on a reference 2500 nm thick CIGSe solar cell (28 mA.cm-2). Lambertian back reflectors are therefore found to be the most effective way to enhance the efficiency of an ultrathin CIGSe solar cell up to the level of a reference thick CIGSe solar cell.

Depuis le début de la microélectronique, l’industrie a développé sans arrêt des nouvelles technologies de gravure plasma pour diminuer la taille des dispositifs tout en réduisant le cout de fabrication et en augmentent les performances des circuits intégrés. Aujourd’hui, les transistors tel que le FDSOI 22nm ou FinFET 10 nm doivent être gravé avec une précision sub-nanométrique et sans endommager la sous-couche sur plus d’une couche atomique. Pour arriver à faire cela, de nouvelles technologie se développent, dont le Smart Etch. Cette technologie en deux étapes consiste à modifier la surface du matériau sous l’action d’un plasma, puis à retirer ce matériau modifié sélectivement par rapport au matériau non modifié. Le but de cette thèse est d’étudier la faisabilité de remplacer les plasmas de He et H2 utilisé dans le Smart Etch par des plasmas d’O2. L’intérêt est l’oxydation du matériau est une réelle modification chimique, permettant l’élimination sélective de ce dernier en RPS. Par ailleurs, contrairement aux plasma de He/H2, le plasma de O2 ne grave pas les parois du réacteur et rejette beaucoup moins d’impuretés dans le plasma. Dans un premier temps, nous avons étudié les mélanges gazeux NF3/H2 et NF3/NH3 utilisés dans l’étape de retrait RPS. Ces études ont été fait grâce à la spectroscopie d’absorption VUV et d’émission UV. Nous avons mis en évidence la création de HF dans les deux mélanges et nous avons mis en avant de manière indirecte la création de NH4F (cette espèce jouant un rôle clé dans la formation des sels) à partir de NH3 et HF. De plus nous avons observé la présence de F et H qui sont responsable de la gravure de SiO2 et SiN lorsque H2<NF3 et NH3<NF3. Dans un second temps, nous avons étudié par XPS angulaire et ellipsométrie l’implantation des ions oxygène dans du SiN avec différent flux et énergie ionique. Cela a bien montré que le SiN initial est transformé en une couche SiOxNy avec une contribution SiO2 importante, sous réserve que l’état stationnaire soit atteint (il faut une dose d’ions significative pour cela). Le flux, l’énergie des ions et le temps de traitement sont donc les paramètres clés pour le contrôle de la couche modifié. Enfin, des tests préliminaires de gravure cyclique de SiN pleine plaque en mode « ALE » (c’est dire monocouche atomique par monocouche atomique) ainsi qu’en mode standard (retrait de quelques nanomètres / cycle) montrent que le principe de gravure est réaliste. Ce travail ouvre donc la voie au développement de ce nouveau type de procédé. / Since the beginning of microelectronics, the industry has continuously developed new plasma etching technologies to reduce the size of devices while reducing the cost of manufacturing and increase the performance of integrated circuits. Today, transistors such as 22nm FDSOI or 10nm FinFET must be engraved with sub-nanometric precision and without damaging the underlayment on more than one atomic layer. To achieve this, new technologies are developing, including the Smart Etch. This two-step technology involves modifying the surface of the material under the action of a plasma and then removing selectively the modified material from the unmodified material. The aim of this thesis is to study the feasibility of replacing the He and H2 plasmas used in the Smart Etch by O2 plasmas. The interest is the oxidation of the material, that it is a real chemical modification, allowing latter the selective elimination by RPS. Moreover, unlike He / H2 plasma, the O2 plasma does not damage the reactor walls and releases much less impurities into the plasma. Firstly, we studied the gaseous mixtures NF3 / H2 and NF3 / NH3 used in the step of RPS remove. Thouse studies were done through VUV absorption spectroscopy and UV emission. We have demonstrated the creation of HF in both mixtures and we have indirectly highlighted the creation of NH4F (this species plays a key role in the formation of salts) from NH3 and HF. In addition we observed the presence of F and H which are responsible for the etching of SiO2 and SiN when H2 <NF3 and NH3 <NF3. Secondly, we studied angular XPS and ellipsometry by implanting oxygen ions in SiN with different flux and ionic energy. This has shown that the initial SiN is transformed into a SiOxNy layer with a significant SiO2 contribution, provided that the stationary state is reached (a significant dose of ions is required for this). Flux, ion energy and processing time are therefore the key parameters for controlling the modified layer.Finally, preliminary tests of full-plate SiN cyclic etching in "ALE" mode (ie atomic monolayer by atomic monolayer) as well as in standard mode (removing a few nanometers / cycle) show that the etching principle is realistic. This work opens the way to the development of this new type of process.

La faible densité et les propriétés mécaniques remarquables des composites polymères en font des matériaux de choix pour remplacer les métaux. Cependant, leurs propriétés physicochimiques rendent leurs surfaces peu adhésives pour divers types de revêtements. Pour améliorer l’adhérence de revêtements métalliques sur des substrats de PEEK, et pour mieux comprendre les mécanismes de l’adhésion, les propriétés de surface du matériau ont été modifiées par des procédés physiques en voie sèche.D’une part, cette étude montre que les traitements par plasma oxydants (à basse pression, ou à pression atmosphérique) permettent d’améliorer la mouillabilité de la surface et l’adhérence de revêtements métalliques, par l’augmentation de la polarité de la surface, quantifiée par XPS. D’autre part, cette étude montre que l’ablation laser infrarouge à impulsion femtoseconde permet la gravure d’un motif dense, induisant de meilleures tenues mécaniques de l’assemblage. Enfin, cette étude montre que la modification de la chimie et de la topographie combinées améliore davantage ce potentiel d’adhérence.Le but de cette étude est d’ouvrir une voie vers un modèle décrivant les mécanismes de l’adhésion, influencés par la chimie de surface et la géométrie d’un motif, en s’appuyant sur un modèle mécanique permettant de décrire la dynamique des contraintes se propageant au travers de l’interface, en tenant compte des propriétés mécaniques des matériaux. / Thanks to their low densities and good mechanical properties, polymer composites are good candidates for metal alloys substitutes. However, their physicochemical properties limit their adhesion potential towards several types of coatings. In order to improve metallic thin films adhesion on PEEK substrates, and to better comprehend adhesion mechanisms, dry-phase methods have been used to alter the surface properties of the material.First, this study shows that oxidative plasma treatments (at low or at atmospheric pressure) improve the wettability and the practical adhesion of metallic coatings, by an increase of the polar component of the surface, as measured by XPS. Second, this study shows that dense patterns etched by an infrared femtosecond laser allow good practical adhesion of the metallic thin films on the substrate. Finally, this study shows that the modification of both surface chemistry and the surface topography at the same time further improves the practical adhesion of the metallic thin films.The goal of this study is to propose a route towards a model describing the combined influence of surface texture and chemistry, with the support of a mechanical model describing the dynamics of the stress dissipation through the interface while taking into account the mechanicals properties of the interfacial materials.

L’objectif de ce travail est d’utiliser les nanoparticules (NPs) de nanosondes fluorescentes de température en particulier dans les films lubrifiants. Le développement de ces nanosondes nécessite la détermination de leurs sensibilités thermiques afin de pouvoir sélectionner les NPs les plus prometteuses. Pour atteindre cet objectif, nous avons présenté deux méthodes d’élaboration utilisées pour la synthèse des nanostructures à base de SiC-3C, la méthode d’anodisation électrochimique et la méthode d’attaque chimique. Dans le premier cas, les analyses FTIR,RAMAN et MET des NPs finales ont montré que la nature chimique de ces NPs est majoritairement formée de carbone graphitique. L’étude détaillée de la photoluminescence de ces NPs a montré que le processus d’émission dépend de la chimie de surface des NPs, du milieu de dispersion et de sa viscosité, de la concentration des suspensions et de la température du milieu. Pour la deuxième famille de NP de SiC, les analyses cohérentes MET, DLS et PL ont montrées une taille moyenne de 1.8 nm de diamètre avec une dispersion de ±0.5nm. Le rendement quantique externe de ces NPs est de l’ordre de 4%. Les NPs dispersées dans l’éthanol, n’ont pas montré une dépendance à la température exploitable pour notre application. Par contre, les NPs de SiC produites par cette voie, étant donné la distribution en taille resserrée et le rendement quantique « honorable » pour un matériau à gap indirect, sont prometteuses pour des applications comme luminophores en particulier pour la biologie grâce à la non toxicité du SiC. Dans le cas des NPs de Si, nous avons également étudié deux types différents de NPs. Il s’agit de : (i) NPs obtenues par anodisation électrochimique et fonctionnalisées par des groupements alkyls (décène, 1-octadécène). Nous avons mis en évidence pour la première fois une très importante variation de l’énergie d’émission dEg/dT avec la température de type red-shift entre 300 et 400K. Les mesures de(T) conduisent à une sensibilité thermique de 0.75%/°C tout à fait intéressante par rapport aux NPs II-VI. De plus il a été montré que la durée de vie mesurée n’est pas fonction de la concentration. (ii) NPs obtenue par voie humide et fonctionnalisées par le n-butyl. Pour ce type de NPs nous avons mis pour la première fois en évidence un comportement de type blue-shift pour dEg/dT de l’ordre de -0.75 meV/K dans le squalane. Pour ces NPs, la sensibilité thermique pour la durée de vie de 0.2%°C est inférieure à celle des NPs de type (i) mais largement supérieure à celle des NPs de CdSe de 4 nm (0.08%/°C). La quantification de cette la sensibilité à la température par la position du pic d’émission dEg/dT et de la durée de vie nous permet d’envisager la conception de nanosondes de température basée sur les NPs de Si avec comme recommandations l’utilisation de NPs obtenues par anodisation électrochimique et de la durée de vie comme indicateur des variations en température. / The goal of this study is the use of Si and SiC nanoparticles (NPs) as fluorescent temperature nanoprobes particularly in lubricating films. The development of these nanoprobes requires the determination of their thermal sensitivity in order to select the best prospects NPs. To achieve this goal, we presented two preparation methods used for the synthesis of 3C-SiC based nanostructures : (i) anodic etching method and (ii) chemical etching method. In the first case, the FTIR, Raman and TEM analysis of final NPs showed that the chemical nature of these NPs is formed predominantly of graphitic carbon. The detailed photoluminescence study of these NPs showed that the emission process depends on the surface chemistry of the NPs, the dispersion medium and its viscosity, the suspension concentration and temperature of the environment.. In the second case, coherent TEM, DLS and PL analyzes showed an average size of 1.8 nm in diameter with a dispersion of ±0.5 nm. The external quantum efficiency of these NPs is 4%. NPs dispersed in ethanol, did not show an exploitable fluorescence dependence on temperature for our application. On the other hand, 3C-SiC NPs produced by this way, given the narrow size distribution and the reasonably high quantum yield for an indirect bandgap material, are promising for applications such as luminophores in particular in the biology field thanks to nontoxicity of SiC. In the case of Si we studied also two different types of NPs. (i) NPs obtained by anodic etching and functionalized by alkyl groups (decene, octadecene). We have demonstrated for the first time an important red-shift in the emission energy dEg/dT with temperature from 300 to 400K. The PL lifetime measurement(T) lead to a thermal sensitivity of 0.75% /°C very interesting compared to II-VI NPs. Furthermore it has been shown that t is not depending on the concentration. (ii) NPs obtained by wet-chemical process and functionalized with n-butyl. For this type of NPs we have identified for the first time a blue-shift behavior of dEg dT in the order of -0.75 meV/K in squalane. The thermal sensitivity for the PL lifetime of these NPs is 0.2%/°C, which is lower than that of NPs obtained by anodic etching method, but much greater than that of CdSe NPs with 4 nm of diameter (0.08%/°C). Quantification of the temperature sensitivity by the position of emission peak dEg/dT and the PL lifetime dτ/dT allows us to consider the realization of temperature nanoprobes based on Si NPs with recommendations to use Si NPs obtained by anodic etching method and PL lifetime as an indicator of temperature changes.

Le Silicium est le deuxième élément le plus abondant dans la croûte terrestre après l’oxygène. Il est produit par voie métallurgique dans un four à arc électrique, le quartz est réduit en présence de réducteurs (charbon de bois, houille et coke de pétrole). Le silicium métallurgique est principalement utilisé dans la métallurgie comme élément d’alliage, dans la chimie et l’industrie solaire. Le prix du Silicium est fonction de sa pureté. Les travaux de cette thèse se divisent en deux parties l’utilisation du Silicium Métallurgique (99% Si) pour le stockage de l’hydrogène, et la photoluminescence du ferrosilicium (disiliciure de fer) de qualité métallurgique. Des substrats de silicium métallurgique ont été soumis à une anodisation électrochimique dans une solution à base d’acide fluorhydrique. Le silicium poreux nanostructuré obtenu est légèrement différent du silicium poreux issu de substrat de silicium de qualité électronique de même résistivité. L’influence des principaux paramètres sur la génération de l’hydrogène : la porosité, la concentration, le volume et la température ont fait l’objet d’une étude détaillée. Le silicium poreux produit à partir de silicium métallurgique est un matériau de stockage d’hydrogène. Des substrats de disiliciure de fer de qualité métallurgique ont été soumis à une anodisation électrochimique. Le composé obtenu est du disiliciure de fer nanostructuré avec du silicium résiduel, ce produit est recouvert de fluorosilicate de fer hexahydraté qui a la particularité d’être luminescent. Il s’agit à ce jour de la première anodisation du disiliciure de fer, un mécanisme de gravure a été proposé et l’influence des principaux paramètres d’anodisation sur les propriétés de photoluminescence a été évaluée. / Silicon is the second most abundant element in the Earth crust after oxygen. Its use in metallurgy, building and electronic industry requires a huge fabrication level. Depending on the contamination level allowed, the price of this material varies in the orders of magnitude. This thesis focuses on the use of dirtiest metallurgical grade silicon and iron disilicide substrates for hydrogen storage and photoluminescence applications. The initial substrates were subjected to electrochemical etching in hydrofluoric acid-containing solutions. Anodization of metallurgical grade silicon substrate produces nanostructured porous silicon with somewhat shifted parameters (comparing with electronic grade porous silicon with the same resistivity), as it was studied in this thesis in details. It was shown, that metallurgical grade porous silicon can be applied as hydrogen storage material. Hydrogen generation is studied here based on the influences of some technically critical parameters: porosity, alkali concentration, volume and temperature. Electrochemical treatment of metallurgical grade iron disilicide substrates produces luminescent iron fluorosilicate hexahydrate, covering the residual nanostructured iron disilicide/silicon. Here, the influence of anodization parameters on photoluminescent properties is studied. Also, etching mechanism is proposed as for the new material never anodized.

Thin polymer films and their properties have been investigated. The characteristics of crystalline polymers according to film thickness have been improved using polycaprolactone (PCL). The melting enthalpy of PCL has increased when the film thickness decreased and the peak melting temperature showed no significant changes with film thickness. Film thickness variation influenced surface roughness and crystal size. Optical microscope images showed the rougher surface of thicker films. The spinning time has shown no influence on film thickness and no significant changes to surface roughness. Thin films of block copolymers were used in the surface modification study; films studied included poly(styrene-b-butadiene-b-styrene) (SBS) and poly(styrene-b-isoprene-b-styrene) (SIS) and their surface modifications have been controlled using different methods of treatment. Films of SIS heated at different temperatures have shown different surface texture and roughness. Films treated at low temperature (45 °C) had smooth surfaces when compared with films heated at high temperature (120 °C and 160 °C). Phase separation of SIS heated at (120 °C and 160 °C) caused bulges of different sizes to cover the surface. The height and width of the bulges showed variation with film thickness and heating. Substrate interaction with SBS and SIS block copolymer films showed different surface texture when using the same type of substrate and different texture were obtained when SBS solutions were spun onto different substrates. It has been demonstrated that using different solvents in copolymer preparation caused different texture. Thermal and surface property variations with film thickness have been improved using amorphous polymers. Surface roughness of poly(methyl methacrylate) PMMA and disperse red 1-poly(methyl methacrylate) DR1-PMMA, PMMA has improved using thickness variation. Glass transition temperature measurement has increased when film thickness was increased. The glass transition temperature (Tg) and surface roughness of UV15 UV - curable coating polymer has been modified using UV curing and heating methods. Tg variation was observed when curing time and curing intensity were changed causing the optical properties of the polymer to be more variable. A plasma etcher caused wrinkles to occur on the surface of unheated UV15. Tg of UV15 increased when curing time increased. The Fourier Transform Infrared Spectroscopy (FTIR) spectra of cured UV15 film have shown peak variations of the ester and carbon double bond regions over the range of 1850-1700 cm-1. Urethane-Urea (UU) Polymer thin films were used to investigate optical properties and develop an optical waveguide. Absorption and transmission properties of light using non-linear optical (NLO) polymer was investigated and used in optical waveguide fabrication. Refractive indices were measured to examine UU films at two different wavelengths. A UU film of 1 µm thickness caused a maximum absorption at max = 471 nm also obtained at 810 nm wavelength. Many methods of fabrication were used; photolithography, plasma etching in a barrel reactor and thin film deposition using sputtering and evaporation. Etched depths from 1 μm to 100 μm were obtained. An optical waveguide has been prepared using plasma etching of a cured UV15 as a cladding layer on a silicon substrate.

This body of research investigated the bonding efficiency of self-etching primer adhesives to enamel and dentine with various surface characteristics. A series of preliminary experiments was carried out to determine the effect of operator experience, dentine tubule orientation, bond strength test method and resin composite material used on bond strengths. The results of the preliminary tests concluded that it is essential to develop skills in material handling and the test methods used; 2-step self-etching primer adhesives exhibit higher but more variable microshear bond strengths (µSBS) than ‘all-in-one’ adhesives on dentine at different depths and tubule orientations; fracture toughness and bond strength test results suggest that the fracture toughness of a resin composite may not be of significant influence on microtensile and µSBS tests outcomes for nano-filled hybrid materials. / An investigation of the bonding ability of self-etching primer adhesives under various tooth preparation conditions was carried out. Enamel and dentine specimens were prepared from human teeth and finished with various rotary cutting instruments and the erbium, chromium:yttrium, scandium, gallium, garnet laser. Specimens were bonded with two 2-step self-etching primer adhesives and two ‘all-in-one’ adhesives with a resin composite. The results showed that one of the 2-step adhesives exhibited higher but more variable µSBS than the ‘all-in-one’ adhesives and a silorane-based self-etching primer adhesive system to enamel and dentine. / The relationship between enamel microhardness and µSBS was evaluated. Enamel specimens were prepared and finished with one half of the surface tested for hardness using the Vickers test. The other half of the enamel surface was bonded using either a 2-step self-etching primer adhesive or an ‘all-in-one’ adhesive and a hybrid resin composite. Mean Vickers hardness numbers and µSBS for each enamel surface were calculated. Analysis using Pearson’s parametric test for regression analysis evaluated the correlation between Vickers hardness and µSBS. The results revealed a weak negative insignificant correlation between VHN and µSBS for the 2-step adhesive and no correlation for the ‘all-in-one’ adhesive. / The effect of conditioning and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) on bonding to bleached and unbleached enamel was investigated. Four groups of enamel specimens: untreated control; bleaching with 16% carbamide peroxide gel for 90 min daily x 14 days; treated with CPP-ACP paste (Tooth Mousse, GC Corp., Japan) for 60 min daily x 7 days and bleached and CPP-ACP-treated were used. The specimens were divided into a further two groups and bonded with a total-etch adhesive or a 2-step self-etching primer adhesive. Specimens bonded with the self-etching primer adhesive were sub-divided into four conditioning subgroups before bonding: no conditioning; 30 – 40% phosphoric; 15% EDTA; 20% polyacrylic acid. Specimens were tested in shear mode until failure and analysed by 2-way ANOVA, one-way ANOVA and Tukey’s post-hoc test. The µSBS of the total-etch adhesive was not affected by enamel treatment. Bleaching reduced the µSBS of the self-etching primer adhesive but preconditioning with phosphoric acid and polyacrylic acid improved bond strengths after CPP-ACP application. Bond failure analysis revealed a predominance of adhesive failures after bleaching, but prior conditioning reduced the proportion of adhesive failures. Scanning electron microscopy (SEM) revealed that the interfacial morphology produced by the 2-step self-etching primer adhesive was independent of enamel treatment except after bleaching. Phosphoric acid etching was not inhibited by CPP-ACP treatment. Resin tag formation was observed with prior phosphoric acid and polyacrylic acid conditioning. / The effect of conditioning and CPP-ACP application on dentine bonding was also investigated. Dentine specimens with and without the smear layer were prepared and divided into a further two groups, CPP-ACP paste applied to one group for 60 min daily x 7 days and the other group was untreated. The two groups were divided into three subgroups for conditioning: no conditioning; 30 - 40% phosphoric acid; 20% polyacrylic acid. The dentine was bonded using a 2-step self-etching primer adhesive and an ‘all-in-one’ adhesive, and tested as previously described. Statistical analysis was carried out using one-way ANOVA and Tukey’s post-hoc test at α = 0.05. The results showed that the µSBS of both adhesives were not significantly affected on smear-covered dentine but was affected on smearless dentine. Conditioning did not improve bond strengths. Bond failure analysis showed more adhesive failures for the ‘all-in-one’ adhesive, particularly on smearless dentine and with prior polyacrylic acid conditioning. SEM revealed a similar morphology of the bonded interface for the 2-step self-etching primer adhesive regardless of conditioning; and areas of bond failures for the ‘all-in-one’ adhesive. / The 2-step self-etching primer adhesives exhibited higher bond strength and more regular bond integrity than the ‘all-in-one’ adhesives, as shown on the SEM observations. However, the ‘all-in-one’ adhesives exhibited less variability in bond strengths to tooth surface characteristics.

Photonic crystals (PhCs) are periodic dielectric structures that exhibit a photonic band gap; a range of wavelengths for which light propagation is forbidden. 2D PhCs exhibit most of the properties as their three dimension counterparts with a compatibility with standard semiconductor processing techniques such as epitaxial growth, electron beam lithography, Plasma deposition/etching and electromechanical lapping/polishing. Indium Phosphide (InP) is the material of choice for photonic devices especially when it comes to realization of coherent light source at 1.55 μm wavelength. Precise engineering of the nanostructures in the PhC lattice offers novel ways to confine, guide and control light in phonic integrated circuits (PICs). Strong confinement of light in PhCs offer novel opportunities in many areas of physics and engineering. Dry etching, a necessary process step in PhC device manufacturing, is known to introduce damage in the etched material. Process induced damage and its impact on the electrical and optical properties of PhCs depends on the etched material, the etching technique and process parameters. We have demonstrated a novel post-etch process based on so-called mass-transport (MT) technology for the first time on InP-based PhCs that has significantly improved side-wall verticality of etched PhC holes. A statistical analysis performed on several devices fabricated by MT process technology shows a great deal of improvement in the reliability of optical transmission characteristics which is very promising for achieving high optical quality in PhC components. Several PhC devices were manufactured using MT technology. Broad enough PhC waveguides that operate in the mono/multi-mode regime are interesting for coarse wavelength de-multiplexing. The fundamental mode and higher order mode interaction creates mini-stop band (MSB) in the dispersion diagram where the higher order mode has a lower group velocity which can be considered as slow light regime. In this thesis work, the phenomena of MSBs and its impact on transmission properties have been evaluated. We have proposed and demonstrated a method that enables spectral tuning with sub-nanometer accuracy which is based on the transmission MSB. Along the same lines most of the thesis work relates to broad enough PhC guides that operated in the multimode regime. Temperature tuning experiments on these waveguides reveals a clear red-shift with a gradient of dλ/dT=0.1 nm/˚C. MSBs in these waveguides have been studied by varying the width in incremental amounts. Analogous to semiconductors heterostructures, photonic heterostructures are composed of two photonic crystals with different band-gaps obtained either by changing the air-fill factor or by the lattice constant. Juxtaposing two PhC and the use of heterostructures in waveguide geometry has been experimentally investigated in this thesis work. In particular, in multimode line defect waveguides the “internal” MSB effect brings a new dimension in single junction-type photonic crystal waveguide (JPCW) and heterostructure W3 (HW3) for fundamental physics and applications. We have also fabricated an ultra-compact polarization beam splitter (PBS) realized by combining a multimode waveguide with internal PhC. MSBs in heterostructure waveguides have shown interesting applications such as designable band-pass flat-top filters, and resonance-like filters with high transmission. In the course of this work, InGaAsP suspended membrane technology was developed. An H2 cavity with a linewidth of ~0.4 nm, corresponding to a Q value of ~3675 has been shown. InGaAsP PhC membrane is an ideal platform to study coupled quantum well/dot-nanocavity system. / <p>QC 20120831</p>